Breaking down the R-44 and 10-14-88 battery thing a bit...(bear with me, I had a margarita or two tonight...)
The 10-14-88 is rated at 88 watt-hours (WH). Many people (including myself) find WH a bit confusing. Most batteries are rated in amp-hours (AH), not WH. Theoritical run-time calculations are easier when using AH. To calculate theoretical run-time1 with a battery spec'd in AH, simply divide the AH spec of the battery by the amp (A) draw of the device one is running. For example, a 7 AH battery using a 1 A device will provide a theoretical run-time of 7 hours (7 AH divided by 1 A).
For a battery spec'd in WH (att-hours), it's easiest if we first convert WH to AH. Then, we may use the simple calculation noted above. To convert a battery's WH to AH, divide the WH rating by the voltage (V). So, using the 10-14-88 battery as an example: an 88 WH battery using a 10V device (for example, the R-442) provides 8.8 AH of capacity (88 WH divided by 10V = 8.8 AH). Going back to the run-time calculation above based on AH: since the battery's AH rating is 8.8 AH, and the R-44 draws 1.2A, the theoretical run-time is 8.8 AH divided by the 1.2 A draw, or 7.3 H (hours).
1Note this is the theoretical run-time, which assumes perfect efficiency. Actual run-times will be somewhat shorter.
2While the R-44 runs on 9V - 16V, the 10-14-88 battery runs on 10V - 14V. For our calculations, we must use the lowest common voltage between the device (R-44) and battery (10-14-88): 10V.
HTH.